From Robert Leslie
No. 12, Aldersgate Street, London July the 24th 1793
I take the liberty of informing you, that I am now in London, whare I expect to stay three or four years, I had not time to finish the Clock and Pendulum, which I had the honour to propose to you, before I left Philadelphia, I have brought it over with me, and shall in the corce of this winter make all the necessary Experiments for fixing a Standard of weights and measure.1
The Secretary of State in his report say, “let it be a Rod that will vibrate Seconds in Lat. 45,”2 but as there is no convenient place in that Lat. in America, and this place is Lat. 51, which is just the same distance from 45 that Philadelphia is, perhaps it might be as well to adjust the rod here, as the Lat. of Greenwich is known in all parts of the world, and there is some of the best timekeepers, which I can have the use of, to regulate it by, and send it over fit for Immediate use.3
If this plan should meets your Approbation I will perhaps be able to compleat the experiment by the time that Congress pass, the Act for regulating weights and measure.4 I am Sir with the highest Respect your Excellencys very humble Servent
ALS, DLC: Jefferson Papers.
1. On Leslie’s earlier announcement of his plans to leave Philadelphia for London, see his letter to GW of 23 Mar. 1793. For Leslie’s ability as a horologist and a description of some of his inventions as of 1789, see Leslie to GW, 20 April 1789, and source note. No written proposal from Leslie to GW on a clock and pendulum has been found. For his work on a vibrating rod for use in establishing an accurate system of weights and measures, see Thomas Jefferson to Leslie, 27 June 1790, Leslie to Jefferson, 1 July, 1790, and “Report on Weights and Measures,” July 1790, editorial note, Jefferson Papers description begins Julian P. Boyd et al., eds. The Papers of Thomas Jefferson. 40 vols. to date. Princeton, N.J., 1950—. description ends , 16:576–77, 588–89, 602–17. On the pendulum that Leslie patented in 1793, see G. H. Baille, Watchmakers and Clockmakers of the World (London, 1929), 225. On his 1795 patents for a nautical watch and for a short pendulum to vibrate seconds, see Harry Leonard Nelthropp, A Treatise on Watch-work, Past and Present (London, 1873), 103.
2. See “Final State of the Report on Weights and Measures,” 4 July 1790, Jefferson Papers description begins Julian P. Boyd et al., eds. The Papers of Thomas Jefferson. 40 vols. to date. Princeton, N.J., 1950—. description ends , 16:650–74.
3. The respective latitudes of Philadelphia, London, and Greenwich, England, are 40°, 51.5°, and 52° north.